The pigment involved in perceiving light for photoperiodism is:

Phytochrome is a photoreceptor pigment that plants use to detect light. It is particularly sensitive to red and far-red light and plays a crucial role in regulating various developmental processes, including seed germination, stem elongation, leaf expansion, and photoperiodic induction of flowering.

• Chlorophyll and carotenoids are photosynthetic pigments.
• Xanthophyll is an accessory photosynthetic pigment.